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A Review of Open and Closed Kinetic Chain Exercise
Following Anterior Cruciate Ligament Reconstruction
By Anthony C. Miller

The following article has been reproduced by kind permission of
the author, Tony Miller. The article is
an abstract on a review of open and closed kinetic chain exercise following
anterior cruciate ligament reconstruction that formed part of his submitted
thesis for his masters degree. Tony studied at the Midwestern State University,
completing his Master's of Science in Kinesiology in 1999. As a graduate
student, he was able to study under Dr. Lon Kilgore, one of USA's most
respected strength coaches.

Abstract

Over the past ten years there has been a steady argument from
physicians, therapists, and coaches over which form of kinetic exercise is most
beneficial following anterior cruciate ligament (5) (ACL) reconstruction (Fig.
1).

Figure 1 - Anatomy of the Knee

Some of the therapists tend to agree that open kinetic chain
exercise (OKCE) benefits the ACL the best. While some therapist believe that
closed kinetic chain exercise (CKCE) are superior to OKCE. Recently, ACL
ruptures have become the most common knee injury involved in the world of
sports. There are approximately 250,000 ACL injuries in a given year (2). These
injuries occur due to shear force placed on the ligament during any type of
decelerating, turning, planting and cutting, and different types of landings.
The ACL can only with stand 400 pounds of pressure at any given time, injuries
become more common in high impact sports (10). With injuries becoming more
frequent, rehabilitation is becoming more important. The purpose of this review
was to determine which form of kinetic chain exercise, open or closed, is most
beneficial following ACL reconstruction. We analyzed the areas that are most
crucial during rehabilitation, strain, stability, joint force, range of motion
(ROM), and strength. We believe that following ACL reconstruction, the safest
Kinetic Chain Exercise will decrease stress, strain, and an increase in
stability as well as range of motion (11)

Kinetic Chain Exercises

During any exercise regiment, whether for rehabilitation purposes
or for strengthening purposes, there are two types of Kinetic Chain Exercises
used. The first is Open Kinetic Chain Exercises (OKCE). These exercises are
performed typically were the foot is free to move. These exercises are
typically non-weight bearing, with the movement occurring at the knee joint
(4). If there is any weight applied it is applied to the distal portion of the
limb. Examples of these exercises would be knee extensions and straight leg
raises. OKCE concentrates on a strong quadricep contraction, which will
strengthen the quadriceps and restore quadricep power output (8).

The second exercise used is Closed Kinetic Chain Exercise (CKCE).
CKCE are performed where the foot is fixed and cannot move. The foot remains in
constant contact with the surface, usually the ground or the base of a machine
(8). These exercises are typically weight bearing exercises, where an athlete
or patient uses their own body weight and/ or external weight. When external
weight is added, it is usually rested across the back of the shoulders or the
front of the chest. Examples of these exercises would be the Squat (both front
and back), Leg Press, Lung, Power Clean, and Snatch. CKCE concentrates on a
co-contraction of the quadriceps, hamstrings, hip flexors, soleus, and
gastrocnemius muscles (9). In addition, this is a multi-joint movement, which
focuses on the knee, hip, and ankle. CKCE are labelled as being "sport specific
movements" (11).

External Forces

During Kinetic Exercises, there are typically two kinds of
external forces: shear and compression. Figures 2 and 3 give examples of each
type of force. Figure 2 shows the angles of shear force placed on the knee
joint during OKCE and CKCE. Figure 3 shows the ACL with shear and compression
forces placed upon it (6).

Figure 2 - Shear force during kinetic
exercises

Shear force, is the force which causes a disruption of the ACL by
shifting the tibia anteriorly and the femur posteriorly. This is caused from
the strong contraction of the quadriceps, which is typical of the Open Chain
Exercise. This force, which is placed on the front of the knee, places a large
amount of stress on the ACL.

Compression force is caused from a strong external force placed on
the knee, which pushes the head of the femur together with the head of the
tibia. This external force causes stability in the knee and a decrease in shear
force. Compression forces are common in Closed Chain Exercises (3, 6).

Review of Literature

Following ACL reconstruction, the rehabilitation is the most
important aspect of restoring the knee joint back to normal levels of
competition. Over the past decade there have been a number of studies that
focus on the rehabilitation of the ACL (5). Due to the extensive research in
this field there are still differences in opinions among many people involved
in the athletic community (11).

Koch (6), in a popular magazine essay, states CKCE produces a
minimal amount of shear force, while OKCE produces a great amount of shear
force. When the knee is extended during Kinetic Chain Exercises, there is a
strong contraction of the quadriceps. Koch found that with CKCE there is a
co-contraction of the quadriceps and hamstrings (6). This reduces shear force
placed on the knee by stabilizing the knee joint. Opposing to OKCE which
increases shear force on the knee joint. This is caused from the lower leg
shifting anteriorly which places a significant amount of stress on the ACL
(Fig.'s 2 & 3).

Figure 3 - Joint Forces

Previous research performed comparing OKCE and CKCE found that
CKCE was a safer and more beneficial from of exercise. Pincivero et al. (12)
found that CKCE reduced shear force and increased compression force in the knee
joint (Fig. 3). Also they found that CKCE activated the hamstrings, which
increase knee stability. This occurs because with the contraction of the
hamstrings, the quadriceps are neutralized from pulling the tibia forward,
which decrease anterior tibial displacement (3).

Escamilla et al. (3) found that there was a large amount of
quadricep activity during both exercises (quadricep contraction causes anterior
tibial displacement). They found that strain place on the ACL during exercise
is directly related to the shear force placed on the knee joint (3). When shear
force is decreased this leads to a decrease in anterior tibial displacement.
During CKCE the hamstrings are contracted, which reduces anterior tibial
displacement. These results are similar to Jenkins et al.'s study (5). This
study found that OKCE increases anterior displacement of the tibia. In
addition, shear force is increased with OKCE.

In 1997 Fitzgerald (4) found that there were no significant
differences between OKCE and CKCE. In this study Fitzgerald believes there is a
place for both kinetic exercises during ACL rehabilitation.

Conclusion

Rehabilitation is the most important stage following ACL rupture.
It is very important to understand what each form of kinetic exercise does to
the knee joint (1). As coaches, trainers, physicians, and therapists we must
understand the strain, joint forces (Fig. 3), and torque placed on the knee
during each exercise. Also we must acknowledge which exercises, cause
stability, an increase in compression force, as well as increased ROM, which
will benefit the patient during rehabilitation.

The most important aspect is to return the athlete back to
pre-injury competition level, as safe as possible (11). In order to do this we
must utilize the exercises that will prevent re-injuring the repaired ACL. This
review of literature found that Closed Kinetic Chain Exercises are the most
beneficial during rehabilitation of the repaired ACL. Also CKCE are the most
beneficial exercises used for prevention of future injuries of the knee joint
(5, 6, 7).

Recommendations

We believe that there needs to be more research, which focuses
mainly on comparing OKCE and CKCE. Of the studies found, only one study that
supported OKCE and only one found that there were no significant differences
between OKCE and CKCE. The rest of the studies concentrated on advantages and/
or disadvantages of either one Kinetic Chain Exercise or the other. There were
only a few articles, which compared directly Open and Closed Kinetic Chain
Exercises